A possible role of central dopamine metabolism associated with individual differences in locus of control

This study investigates the relationship between dopamine metabolism and a personality trait, the locus of control. For 29 primary breast cancer patients who are otherwise normally functioning, plasma concentrations of homovanillic acid (pHVA) levels and locus of control on the Rotter internal–external scale were determined. The results indicate that pHVA is significantly associated with locus of control, with pHVA levels increasing for more externally oriented individuals. This relationship held true when age and four different stress-related measures were partialled out. These findings are discussed with respect to individual differences in higher cognitive functions requiring sustained prefrontal cortical activity, and a neural model of central dopamine regulation.